Leptospirosis is a worldwide zoonotic disease caused by spirochetes of the genus Leptospira. The clinical manifestation of leptospirosis is non-specific and frequently misdiagnosed as other illnesses. The aim of this study was to compare the diagnostic accuracies of two commercial tests for early diagnosis of Leptospira species: the IgM latex agglutination test (IgM LAT) and the IgM enzyme-linked immunosorbent assay (IgM ELISA). A total of 140 serum samples were obtained from patients suspected of leptospirosis at the Universiti Kebangsaan Malaysia Medical Centre (UKMMC). These serum samples were tested for the presence of Leptospira sp. using IgM LAT, IgM ELISA and MAT. From Table 1, IgM LAT showed 21% (n = 29) positive, 18% (n = 25) inconclusive and 61% (n = 86) negative, while IgM ELISA showed 6% (n = 8) positive, 6% (n = 8) inconclusive, 88% (n = 124) negative and MAT showed 11% (n = 16) positive, 47% (n = 65) inconclusive, 42% (n = 59) negative. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of IgM LAT were 68.8%, 57.6%, 30.6% and 87.2% respectively, while for IgM ELISA they were 37.5%, 89.8%, 50% and 84.1%, respectively as compared to MAT (Table 2). The results showed that IgM LAT had higher sensitivity but lower specificity compared to IgM ELISA. In conclusion, IgM LAT can be useful as an early screening test for early diagnosis of Leptospira sp., while IgM ELISA is a suitable method for reducing false negative detection of Leptospira sp. As both tests show moderate percentages (~65%) in accuracy, an additional test is required for better detection of Leptospira sp.
Luminescence-based assays for toxicants such as Microtox, ToxAlert, and Biotox have been used extensively worldwide. However, the use of these assays in near real time conditions is limited due to nonoptimal assay temperature for the tropical climate. An isolate that exhibits a high luminescence activity in a broad range of temperatures was successfully isolated from the mackerel, Rastrelliger kanagurta. This isolate was tentatively identified as Photobacterium sp. strain MIE, based on partial 16S rDNA molecular phylogeny. Optimum conditions that support high bioluminescence activity occurred between 24 and 30°C, with pH 5.5 to 7.5, 10 to 20 g/L of sodium chloride, 30 to 50 g/L of tryptone, and 4 g/L of glycerol as the carbon source. Assessment of near real time capability of this bacterial system, Xenoassay light to monitor heavy metals from a contaminated river running through the Juru River Basin shows near real time capability with assaying time of less than 30 minutes per samples. Samples returned to the lab were tested with a standard Microtox assay using Vibrio fishceri. Similar results were obtained to Xenoassay light that show temporal variation of copper concentration. Thus, this strain is suitable for near real time river monitoring of toxicants especially in the tropics.
Margalefidinium polykrikoides, an unarmored dinoflagellate, was suspected to be the causative agent of the harmful algal blooms - associated with massive fish mortalities - that have occurred continually in Lampung Bay, Indonesia, since the first bloom event in October 2012. In this study, after examination of the morphology of putative M. polykrikoides-like cysts sampled in bottom sediments, cyst bed distribution of this harmful species was explored in the inner bay. Sediment samples showed that resting cysts, including several morphotypes previously reported as M. polykrikoides, were most abundant on the northern coast of Lampung Bay, ranging from 20.6 to 645.6 cysts g-1 dry sediment. Molecular phylogeny inferred from LSU rDNA revealed that the so-called Mediterranean ribotype was detected in the sediment while M. polykrikoides motile cells, four-cell chain forming in bloom conditions, belonged to the American-Malaysian ribotype. Moreover, hyaline cysts, exclusively in the form of four-cell chains, were also recorded. Overall, these results unequivocally show that the species M. polykrikoides is abundantly present, in the form of vegetative cells, hyaline and resting cysts in an Indonesian area.
Red tides and associated fisheries damage caused by the harmful raphidophyte Chattonella were reassessed based on the documented local records for 50 years to understand the distribution and economic impacts of the harmful species in the Western Pacific. Blooms of Chattonella with fisheries damage have been recorded in East Asia since 1969, whereas they have been only recorded in Southeast Asia since the 1980s. Occurrences of Chattonella have been documented from six Southeast Asian countries, Indonesia, Malaysia, Philippines, Singapore, Thailand and Viet Nam, with mass mortalities mainly of farmed shrimp in 1980-1990s, and farmed fish in 2000-2010s. These occurrences have been reported with the names of C. antiqua, C. marina, C. ovata, C. subsalsa and Chattonella sp., owing to the difficulty of microscopic species identification, and many were not supported with molecular data. To determine the distribution of C. marina complex and C. subsalsa in Southeast Asia, molecular phylogeny and microscopic observation were also carried out for cultures obtained from Indonesia, Malaysia, Japan, Philippines, Russia, Singapore and Thailand. The results revealed that only the genotype of C. marina complex has been detected from East Asia (China, Japan, Korea and Russia), whereas both C. marina complex (Indonesia and Malaysia) and C. subsalsa (Philippines, Singapore and Thailand) were found in Southeast Asia. Ejection of mucocysts has been recognized as a diagnostic character of C. subsalsa, but it was also observed in our cultures of C. marina isolated from Indonesia, Malaysia, Japan, and Russia. Meanwhile, the co-occurrences of the two harmful Chattonella species in Southeast Asia, which are difficult to distinguish solely based on their morphology, suggest the importance of molecular identification of Chattonella genotypes for further understanding of their distribution and negative impacts.